1,2,4-triazin-5(4H)-ones substituted at the 4-position by an amino moiety, at the 6-position by an alkyl moiety and at the 3-position by an alkylthio moiety form a well-known class of herbicides, claimed in U.S. Pat. No. 3,671,523. One species, 4-amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5(4H)-one, commonly known as metribuzin, is a commerical product, marketed under the trademark "Sencor".
However, such compounds are very soluble in water, and thus susceptible to being leached from soil by rainfall or irrigation water.